1. Field of the Invention
The present invention relates to bicycle transmissions and drivetrain assemblies. More specifically, the present invention relates to a bicycle with an internal gear set for transmitting user power to a hubless wheel through a drivetrain assembly housed within an interior cavity of the bicycle frame.
2. Description of the Prior Art
Bicycle devices are common transportation and recreational devices utilizing two wheels, a chain and sprocket gearing mechanism, pedal input, steering mechanism and associated controls. These devices are well described in the art, and have undergone considerable changes since their inception. These changes include updates to the bike structure, as well as the mechanical systems that drive the bicycle. These vary from updated materials and frame styles, different tires styles and technology, wheels to accommodate different terrain types, various levels of suspension sophistication, and most relevantly the advances in bicycle transmission mechanisms. Motive power is traditionally transferred via a user-driven crank using foot pedals to power a drive sprocket, which advances a chain linkage secured between the drive sprocket and a rear sprocket. Both sprockets may include concentrically aligned sprockets of differing radius that provide differing speed ratios with regard to the user input and the rear wheel output rotation. The chain is shifted from one sprocket to another to adjust gear ratios for the user, allowing greater torque or higher speeds as required. This type of drive mechanism is a standard assembly for most available bicycles, providing a simple mechanism and method of transferring power and changing gear ratios.
While there are clear benefits derived from this type of mechanism, including simplicity, lightweight and effectiveness. However, there lies room to update this transmission to a more sophisticated and robust means of transferring user-powered rotation to the rear wheel, along with associated gear ratio updating. Common problems associated traditional bicycle transmissions involve the bicycle chain and sprockets. This mechanism is prone to chain slippage or complete dislocation, which disables the vehicle and prevents transference of motive power to the wheel. Another common problem lies in the location of the chain and sprocket assemblies, namely its location exterior of the vehicle frame and in close proximity to a pedaling user. This exposed mounting allows dirt and debris to freely enter the mechanism, increasing maintenance of the system and the susceptibility of the system to foreign object debris and damage. Rocks and dirt can cause the system to lose lubrication and create an interference problem while riding, which endangers the mechanisms and the rider. A further concern is the propensity of the drive gear and chain to snag articles of clothing worn by the rider and cause damage thereto. It is common to see riders hiking up articles of clothing along their legs to prevent such occurrences. The exposed mechanism is also able to fling grease and debris onto the riding user, which can soil his or her clothing during riding.
An update to the traditional bicycle is required, one that addresses the aforementioned drawbacks of the common sprocket and chain mechanism. The present invention provides a fresh update to the bicycle device by providing one that includes a frame having an internal volume, a transmission located therein, incorporation of hubless wheels, and the ability to robustly and quickly adjust gear ratios of said transmission. Further benefits include the ability of the bike wheels to be decoupled from the central frame, and the ability of the forward handle bars to freely rotate about its mounting stem. A handle bar rod mechanism, mounted within the handle bar stem, provides control linkages for all mechanical systems, including gear shifting and brake application.
Several devices are described in the art that employ similar mechanisms or means for delivering power via a direct drive transmission or with a hubless wheel. However, these devices include drawbacks inherent in their design that either limit their use or fail to describe the novelty provided in the present disclosure.
U.S. Pat. No. 5,378,201 to Lee is one such device that describes a transmission assembly for a bicycle that can adjust the torque and velocity through an internal gearing mechanism that requires no variation in sprocket diameter. The device includes a chain drive and a series of gear sets and sprockets to affect quick shifting and a more robust means of maintaining the chain on the system. The Lee device provides a simplified structure for a bicycle transmission; however the device construction and constitutive parts differ when compared to the present invention. The Lee device is maintains a chain-driven system and a series of sprockets. The present invention substitutes all sprockets and chains for a discrete gear drive system, utilizing meshed gears, pinions and shafts to transmit power from the foot pedal crank to the rear wheel.
U.S. Published Patent Application No. 2009/0062057 to Fujiwara is another device that describes a covered bicycle transmission for a typical bicycle type, comprising a main shaft and plurality of gears to allow changes in output torque and speed as required. The device is mounted along the foot pedal crank and allows improved gear changing operation. Its structure is sufficiently simple and compact in size to allow incorporation onto existing bicycles using general-purpose parts to change speed ratios smoothly and effectively. While providing a means to seamlessly change gear ratios, this device falls short of describing the present invention, which provides a new type of bicycle with a completely internal gear train and power delivery means to a preferably hubless wheel. The present invention further provides a means of changing gears by operably translating a plurality of drive axles radially inward or outward from a main drive gear and a final drive gear, allowing high and low speed adjustments without requiring a plurality of aligned gears that operate independently.
U.S. Pat. No. 3,861,715 to Mendoza describes a direct transmission system for a bicycle that eliminates the use of a chain and sprocket drive system. A cylindrical axle connects to conical gears that drive the rear wheel, providing an enclosed assembly that reduces interferences with road debris, articles of clothing and further eliminates chain grease dispersion onto a rider's clothes. The Mendoza patent eliminates a chain driven transmission for a bicycle, but is limited in its ability to provide adequate gear ratios for widespread use and acceptance. The device is simplistic, but fails to achieve the level of sophistication required by modern bicyclists for improved use in all situations.
U.S. Pat. No. 5,316,327 to Bell describes a similarly chainless bicycle, comprising a crank hanger assembly that houses drive gears connected to the pedal arms. Support tubes connect the rear wheel to the pedal gear box, housing a drive shaft that transmits power from the pedals to the rear wheel. A bevel gear is provided on each end of the drive shaft to allow rotation of the shaft and torque transmission between the pedals and a rear wheel box. Similar to the Mendoza patent, this direct drive transmission eliminates the use of an exposed chain and sprocket system; however it lacks the ability to provide several speed ratios to the user. Its design and construction are simplistic, limiting its use when compared to the present invention. The present invention provides a direct drive system utilizing a plurality of gearing mechanisms, control rods and drive shafts that provide a user with a seamless transition from a standard, multi-speed bike to a direct drive, multi-speed bike with improved features and obvious advantages.
U.S. Pat. No. 5,419,619 to Lew describes a hubless wheel for a vehicle that improves weight and aerodynamic performance over a standard hub and spoke wheel. The wheel comprises a stationary inner loop that is coupled to the vehicle, while a rotatable outer loop concentrically mounted the inner loop. Bearings are provided between the inner and outer loop, while the outer loop is circumferentially mounted with a ground engaging tire tread. The present invention provides a similar hubless wheel in its construction; however the present invention contemplates its use in conjunction with a direct drive transmission that employs a gear pitch radially provided along the wheel. The direct drive transmission distributes power to the wheel through a meshed pair of beveled gear and the radial gear pitch along the rotating wheel. Its construction differs from the Lew patent, although both provide a hubless wheel with weight and aerodynamic advantages over traditional bicycle and vehicle wheels.
The present invention provides a new bicycle structure and associated mechanical drive system to allow all drive mechanisms to be internal to a central frame. A drivetrain of gears, pinions, bevel gears, drive axles and bushing provide means to transmit motive power from a user to the rear wheel. The wheels themselves are preferably hubless wheels, utilizing a rotating wheel member in connection with a stationary member via bearings. The front and rear wheels are separable from the frame itself, while all user controls are input through linkages provided within the handlebar stem. The drivetrain allows selection of different gear ratios, including high and low adjustment. The present invention substantially diverges in design elements from the prior art and consequently it is clear that there is a need in the art for an improvement to existing bicycle devices. In this regard the instant invention substantially fulfills these needs.